* Exploration can proceed after U.S. drilling expansion
* Shell’s Odum says company can begin exploring in 2010
* Shell spent $2.1 billion for Chukchi Sea leases in 2008
* ConocoPhillips spent $506 million on leases
By Kristen Hays
HOUSTON, March 31 (Reuters) – Oil companies with their sights on drilling for oil off Alaska on Wednesday said President Barack Obama’s offshore oil announcement allows them to press ahead with big projects there.
Two companies — Royal Dutch Shell (RDSa.L) and ConocoPhillips (COP.N) — have spent large sums to secure drilling rights in the remote Chukchi Sea, only to see their plans put on hold by court challenges.